[lan]

Quote:

Originally Posted by akwok Am I the only one who can't hear the purported changes in jitter between different computer transports? It all sounds the same to me. It's also funny to see how according to different people, lower jitter changes different aspects of the sound, not one specific element.

I have to agree computer transports sound nearly all the same BUT only because they are not the best and are in the same ballpark of performance.

As with many forms of perception, the communication of it is hard to convey.

Quote:

Originally Posted by nightfire Does an i2c transport->dac link bring a .flac close to the analog level of cymbal purity?

The link is just one part of the whole system. While it's important, you'll have to have the other parts good also.

Quote:

Originally Posted by audioengr The pits in the CD are spacially located. This is what creates the timing when the disk is spinning.

Most people won't believe this makes a difference. I just made discs for people and those who've heard my reburned disc said it was better than the original.

Quote:

Originally Posted by ObiHuang Don't worry, you're not alone. I'm pretty sure the people who actually recorded the music you listen to cared less about "jitter." Whatever extra "jitter" I introduce seems negligible.

Jitter matters the most in the ADC conversion. The rest of their system shouldn't be that much affected by it. Generally it's an esoteric topic. Most people don't care about all these things.

I think that this stance that you have is the kind that some other non-tweak believers have. It also reminds me of the power cord issue where it doesn't matter since it's the last 6 ft after thousands of miles of wire.

I generally think every little thing matters and try to keep an open mind.

Quote:

Originally Posted by LeChuck Jitter is certainly real, given that it can be objectively measured using instruments, but the fact that something can be measured doesn't necessarily mean it will have any kind of audible impact. Just because can measure a noise at 100,000Hz, doesn't mean I'm going to hear it, in fact I have no chance of hearing that. I've heard some people describe jitter as somethin you only notice once it's removed, not when it's present. I think that the fact that no one has a concrete description for what jitter actually sounds like is enough to bring its audible legitimacy into question.

Inversely, something that can't be measured doesn't necessarily mean it can't be heard.

There are things which can only be realized once it's been experienced. Maybe you have not had that revelation yet. The fact that nobody has made a concrete description is fine. What's a fact is that perception, feeling, preferences, etc. are all variable and there is no right or wrong.

 

[audioengr]

Quote:

Originally Posted by Regus I can see some problems with designing a DAC that way: If your clock is even marginally slower that the clock in the device sending you the data you will have a buffer overflow sooner or later, meaning your buffer will need to be rather large for this not to become a seriously anoying issue - without doing the math i would guess well into the MB range. Conversely if your clock is faster you will have nothing but underrun. And whatever you do you will need a clock that is slower than the input in order to ever fill up your buffer, or you will have a significant delay from you start sending data to the DAC before you hear any sound. The problem is significantly different in CD player where you can control your input media (The reading of the CD) - if you make a design that is slightly faster than 1x and allows for pausing you will have an easy time keeping a reasonably sized buffer full at all times.

Precisely. If the CD is spinning faster than the sample-rate, then you can buffer to your hearts content and get a nice jitter-free signal. This is how computer audio works. Buffers blocks in memory and spools them out to USB or WiFi.

Steve N.
Empirical Audio

 

[audioengr]

Quote:

Originally Posted by lan I have to agree computer transports sound nearly all the same BUT only because they are not the best and are in the same ballpark of performance.

At least the computer "transports" that you have heard. I doubt if you have heard all of them....

Steve n.

 

[lan]

Quote:

Originally Posted by audioengr At least the computer "transports" that you have heard. I doubt if you have heard all of them.... Steve n.

I haven't heard them all and neither have most people so I am generalizing that the statement is true for like 99% of all computer transports. Practically for most people it's true.

My system is in that 1% though and you're is probably in <.1%. Most people will never run into systems like yours.

 

[Regus]

Quote:

Originally Posted by audioengr Precisely. If the CD is spinning faster than the sample-rate, then you can buffer to your hearts content and get a nice jitter-free signal. This is how computer audio works. Buffers blocks in memory and spools them out to USB or WiFi.

And give me one reason to design a CD player in an inferior way...

 

[audioengr]

Quote:

Originally Posted by Regus And give me one reason to design a CD player in an inferior way...

Cost. It's what drives all CE.

Steve N.

 

[Regus]

Quote:

Originally Posted by audioengr Cost. It's what drives all CE.

Might be an argument for $50 players - but my portable player in the 1990s had 10s worth of antishock memory and cost less than $150 - which to me spells that any half decent player today should be able to apply similar techonolgy for little or no cost at all - so unless you are using absolute low end gear I sincerely doubt that a cost benefit analysis would end out in favor of the highly enferior possibly slightly more expensive solution.

 

[regal]

Quote:

Originally Posted by audioengr Precisely. If the CD is spinning faster than the sample-rate, then you can buffer to your hearts content and get a nice jitter-free signal. Steve N. Empirical Audio

This would have little if any effect on jitter reduction..

 

[thomaspf]

This has all to do with jitter reduction. If you do not rely on the drive mechanism and the disc speed in any way to determine the clock for the conversion than you can clock the converters with a crystal directly for lowest possible jitter.

You then need to asynchronously read the data from the disc to a buffer that is being emptied from the that crystal clock at a steady rate. This is actually the reason that it is pretty hard to match the performance of an integrated player with a transport DAC combination. In most players the master clock is driving the DAC chips directly.

Coincidentally that is what most players do these days since it cost nothing extra to do it. This is simply how a modern CD chipset works. The single chip CD7 from philips was introduced 1998 and it is very likely you have of these even in your in dash player in the car.

http://www.nxp.com/acrobat_download/.../SAA7373_1.pdf

Cheers

Thomas